Indeed - though don't forget also to divide by the baseline level! You can
use avwmaths:
avwmaths filtered_func_data -Tmean baseline
avwmaths stats/cope1 -mul <number> -mul 100 -div baseline percent_change1
and for FSL3.2 FEAT output you can find the <number> (the peak-peak height
of the relevant EVs) in the header of the design.mat or design.con files.
Cheers.
On Fri, 5 Nov 2004, Joseph Devlin wrote:
> Hi Arun,
>
> Essentially you just want to scale the PE maps, since these are already the
> measure of effect size at each voxel in the brain. If you compute the max
> - min height of the individual regressor and multiply the PE image by that
> number, you'll transform the PE image into a % signal change image. If you
> want % signal change copes, then simply add/subtract the transformed PE
> files according to your contrasts and you'll get % signal change copes.
>
>
> Joe
>
> --------------------
> Joseph T. Devlin, Ph. D.
> FMRIB Centre, Dept. of Clinical Neurology
> University of Oxford
> John Radcliffe Hospital
> Headley Way, Headington
> Oxford OX3 9DU
> Phone: 01865 222 494
> Email: [log in to unmask]
>
--
Stephen M. Smith DPhil
Associate Director, FMRIB and Analysis Research Coordinator
Oxford University Centre for Functional MRI of the Brain
John Radcliffe Hospital, Headington, Oxford OX3 9DU, UK
+44 (0) 1865 222726 (fax 222717)
[log in to unmask] http://www.fmrib.ox.ac.uk/~steve
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